The present invention is directed to microtest plate carriers for use on a swinging type of centrifuge rotor and, more particularly, is directed to an overspeed protection device for use on the microtest plate carrier.
Typically, microtest carriers are utilized in a centrifuge where the rotor heads or yokes are designed for relatively high speed applications. Therefore, the rotor frequently is rated and designed to operate at speeds several times the rated safe speed for the carrier itself. The force field associated with high speed centrifugation can result in damage to the carrier when it is rotated at a speed greater than that for which it is designed.
Some approaches to alert the user of microtest plate carriers of this potential problem incorporate some type of caution label which is attached to the carrier stating that it is not to be run above a certain rotational speed or is not to be subjected to a certain G loading. Since the design of the carriers is such that it may survive one overspeed run, without having any visible or readily noticeable deformation or defect, a user does not know if the carrier has previously been subjected to an overspeed condition. However, if a carrier is subjected to a second or third overspeed condition, the probability of significant failure in the carrier is greatly increased. Hence, caution labels are not a complete and adequate safety feature with respect to ensuring the user of the carriers that they have not been previously subjected to an overspeed condition.
An alternative approach would be to design a carrier with a significant margin of safety, so that, if it were run several times over the rated speed, it would have a sufficient resistance to fatigue as well as the higher centrifugal forces and withstand the adverse environment. However, the designing of the carriers with such a high margin of safety would present a prohibitively expensive carrier.